Cyclic alkylmethylsiloxanes for skin care

ABSTRACT

A method of treating human skin to decrease transepidermal water loss. A method of enhancing the substantivity of conditioning compounds applied to the skin. A film forming conditioning formulation which includes as an ingredient thereof an organosilicon compound is applied to the skin. The improvement resides in the utilization of a formulation which includes as the organosilicon compound a cyclic alkylmethyl polysiloxane.

This is a continuation-in-part of application Ser. No. 07/750,135, filedAug. 26, 1991, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to personal care and to certain alkylmethylpolysiloxanes useful in skin care applications. More particularly theinvention is directed to moisturization and to the formation of films onthe skin which function as barriers in order to reduce transepidermalwater loss with the result that skin is softened by virtue of its ownmoisture. In a recent publication by Th. Goldschmidt AG dated July 1989and entitled "ABIL Silicones" it is reported that certain polysiloxanepolyalkylene copolymers known as ABIL-WAX 9800 and ABIL-WAX 9801 haveutility in skin care applications such as day creams, all purpose creamsand body lotions. The materials are said to be soluble in cosmetic oilsand waxes and to protect against aqueous media when employed in amountsof one to five percent by weight. These materials otherwise known underThe Cosmetics, Toiletries and Fragrances Association adopted names ofstearyl dimethicone and cetyl dimethicone have the structural formula:##STR1##

The "ABIL" siloxanes are described as having a linear structure incontrast to the present invention which is in the form of a cyclicstructure. Also the "ABIL" wax described by the Goldschmidt referencecontains residual metal and is not homogenous. In contrast the presentinvention is in a homogenous state and does not contain metallic residuewhich therefore results in a safer and purer product for personal careapplications. The cyclic siloxanes of the present invention are moresubstantive to the skin surface, and form a film on the skin whichfunctions as a barrier to prevent the permeation of moisture upward fromthe skin and through the film. This reduces the transepidermal waterloss from the skin with the result that the skin is softened due to theretention of more of its own moisture. Test data indicate that thecyclic siloxanes of the present invention possess these improvedproperties to an unexpectedly greater degree than the "ABIL" siliconesas will be shown hereinafter.

U.S. Pat. No. 4,574,082 issued Mar. 4, 1986 describes cosmeticscontaining a dimethylpolysiloxane in admixture with linearorganopolysiloxanes such as polymethyloctylsiloxane andpolymethyloctadecylsiloxane. There is no disclosure or description ofcyclic compositions in the '082 patent. By applying films containingonly silicones which are high molecular weight cyclicalkylmethylsiloxanes, it has been possible in accordance with thepresent invention to reduce substantially transepidermal water loss fromthe skin and to therefore provide occlusive moisturizing treatments.

Protective skin creams are described in United Kingdom Patent No.737,134 granted Sep. 21, 1955. These skin creams are said to includecertain hydrocarbon substituted organosiloxanes. The hydrocarbonradicals are noted preferably to be lower alkyl radicals such as methyl,ethyl, and propyl however the British patent indicates that for certainuses higher alkyl radicals such as octadecyl and lauryl radicals may bedesired. There is no description or disclosure of cyclic materials inthe '134 patent. Also the description of the above compositions allowsthe presence of higher alkyl radicals at the ends of the polymer chainin contrast to the cyclic compositions of the present invention.

Skin care lotions and creams said to include mixed C₁ -C₃ alkylpolysiloxanes such as methylethylpolysiloxane are disclosed in U.S. Pat.No. 4,960,764 issued Oct. 2, 1990. Siloxanes including short chain alkylgroups such as ethyl and propyl do not differ significantly fromdimethylpolysiloxanes and therefore the siloxanes of the '764 patentsuffer from the disadvantage of being ineffective moisture barriers asexplained above in detail. Thus methylethylpolysiloxane andmethylpropylpolysiloxane will each possess a high water permeabilitythrough their respective films and will each be incapable of functioningas effective occlusive barriers in comparison to the high molecularweight C₁₂ to C₃₀ cyclic alkylmethylsiloxanes of the present invention.Further short chain alkylmethylpolysiloxanes as described in the '764patent are less durable and their films may be easily removed from thesurface of the skin in contrast to the substantive nature of the filmsformed by the cyclic materials of the present invention.

In U.S. Pat. No. 4,784,844 issued Nov. 15, 1988 there are describedcertain water based emulsions for cosmetic and medicinal applicationwhich are said to contain a cyclic polysiloxane of the formula ##STR2##in which n is an integer from three to ten and z is an integer having avalue of from one to ten. These cyclic materials are stated to bevolatile. In contrast to the '844 patent, the present invention utilizescyclic alkylmethyl polysiloxanes which are non-volatile and which can bedelivered to the skin in the form of an anhydrous medium. In addition,the alkyl group (CH₂)_(z) CH₃ of the '844 is smaller than thecorresponding alkyl group of the cyclic alkylmethyl polysiloxanes of thepresent invention. Thus the alkyl group in the '844 patent varies fromC₂ to C₁₁ whereas the alkyl group of the present invention is C₁₂ toC₃₀.

In U.S. Pat. No. 5,002,762 issued Mar. 26, 1991 there are describedvolatile silicon compounds for household and cosmetic applications whichare stated to contain a cyclic polysiloxane of the formula ##STR3## inwhich Y is an integer from one to four and R can be independently a C1to C10 alkyl group. These silicon compounds are also stated to bevolatile. In contrast to the '762 patent, the present invention utilizescyclic alkylmethyl polysiloxanes which are non-volatile and which can bedelivered to the skin in the form of an anhydrous medium. Also, thealkyl group R of the '762 patent is smaller than the corresponding alkylgroup of the cyclic alkylmethyl polysiloxanes of the present invention.The alkyl group of the '762 patent varies from C₁ to C₁₀ while the alkylgroup in the present invention ranges from C₁₂ to C₃₀.

Accordingly new and novel personal care formulations are provided hereinin which a cyclic alkylmethyl polysiloxane is utilized as a substantivebarrier to water loss to provide soft skin.

SUMMARY OF THE INVENTION

The invention is directed to a method of treating human skin to decreasetransepidermal water loss. The invention is also directed to a method ofenhancing the substantivity of conditioning compounds on human skin. Afilm forming conditioning formulation which includes as an ingredientthereof an organosilicon compound is applied to the skin. Theimprovement resides in the utilization of a formulation which includesas the organosilicon compound a cyclic alkyhnethyl polysiloxane.

The invention is also directed to personal care and to certain cyclicalkylmethyl polysiloxanes useful in skin care applications. Further theinvention is related to moisturization and to the formation of films onthe skin which function as barriers in order to reduce transepidermalwater loss with the result that skin is softened by virtue of its ownmoisture. In addition the invention includes a method for making thecyclic alkylmethyl polysiloxanes and skin care formulations containingcyclic alkylmethyl polysiloxanes.

These and other features, objects and advantages of the presentinvention will be apparent upon consideration of the following detaileddescription of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In order to treat human skin for the purpose of effecting a decrease inthe transepidermal water loss, there is applied to the surface of theskin a film forming conditioning formulation which can be anhydrous. Thealkylmethyl cyclic polysiloxanes are compounds having the formula##STR4##

In the formula x and y are integers the sum of which is four, five, orsix provided that x cannot be zero, and z is an integer which has avalue of eleven to about twenty-nine. R is an alkyl group having one tosix carbon atoms. Typically the R group is methyl although other alkylradicals may be employed. Thus the most preferred compounds have theformula ##STR5## in which x, y and z are as defined above. Thus where xis one y is three, four, or five; where x is two y is two, three, orfour; where x is three y is one, two or three; where x is four y iszero, one, or two; and where x is five y is zero or one.

The cyclic alkylmethylpolysiloxanes can be delivered to the skin as ananhydrous formulation which is applied to the skin in the form of asolution of the cyclic alkylmethyl polysiloxane dissolved in a volatilesolvent such as an aliphatic hydrocarbon, aliphatic alcohol, aliphaticester, or a low viscosity cyclic silicone fluid. Such volatile solventsare described below. The cyclic alkylmethylsiloxanes of the presentinvention can be delivered to the skin as a hydrous or as an anhydrousformulation.

The cyclic alkylmethyl polysiloxanes of this invention can be producedby the reaction of a linear siloxane having Si--H functionality in thechain such as (Me₃ SiO_(1/2))₂ (OSiMeH)_(x) in which Me is methyl and xis forty to about one hundred, and a cyclic siloxane having (Me₂ SiO)units of the formula (Me₂ SiO)_(x) in which Me is methyl and x is aninteger of about three to six preferably four or five. The reactionproduct is about ninety percent by weight of a linear polymer and tenpercent by weight of a cyclic polymer. The reaction product is thencontacted with a slight stoichiometric excess of an alkene CH₂ ═CHR inthe presence of a platinum on carbon catalyst and a cyclicalkylmethylsiloxane having the structure of formula (II) shown above isproduced.

The cyclic alkylmethyl polysiloxanes of this invention can also beproduced by the direct hydrolysis of methylhydrogen dichlorosilane toform cyclomethylhydrogen polysiloxanes, or by the direct cohydrolysis ofmethylhydrogen dichlorosilane and dimethyl dichlorosilane to formcyclomethylhydrogensiloxy dimethylsiloxy copolymers. The reactionproduct is then contacted with a slight stoichiometric excess of analkene CH₂ ═CHR in the presence of a platinum on carbon catalyst and acyclic alkylmethylsiloxane having the structure of formula (II) shownabove is produced.

Batch production of the alkylmethyl polysiloxanes is conducted by addingthe reaction product to a non-agitated suspension of the catalyst in thealkene at about sixty degrees Centigrade. Continuous production of thealkylmethyl polysiloxanes is conducted by pumping a preheated solutionof a five percent stoichiometric excess of an alkene CH₂ ═CHR and thereaction product through a packed column containing platinum on carboncatalyst chips. The column will require provision for the removal ofheat because of the exothermic nature of the reaction.

The materials are further processed in accordance with the presentinvention in order to provide a more cosmetically acceptable product byremoving from the product any remaining cyclic siloxane and any residualmethylhydrogendimethylsiloxane cocyclics present as (MeHSiO)(Me₂ SiO)₃.The alkylmethyl polysiloxanes produced in accordance with the presentinvention have been found to contain at most about 0.5 percent residualalkene and about 99.5 percent alkylmethyl polysiloxane product. Nomeasurable residual amount of platinum has been detected. The productsare otherwise colorless, odorless, non-volatile, clear and stablematerials. The products are particularly adapted to skin care in thatthe materials have been found to form films on the skin which possess avery low water vapor permeability enabling the materials to form abarrier on the skin which will reduce moisture loss from the stratumcorneum. The alkylmethyl polysiloxanes find utility in skin creams andlotions including facial products such as cleaners and moisturizers,hand creams, baby creams and sun care creams and lotions.

The water content of the outer layers of the stratum corneum of humanskin is a controlling factor in the appearance of dry skin symptoms.When the stratum corneum contains an adequate amount of water within therange of ten to twenty percent the skin remains flexible. However whenthe water content falls below ten percent the stratum corneum oftenbecomes brittle and rough and can exhibit scaling and cracking. Thestratum corneum receives its water from the deep layers of the epidermisby diffusion, from ambient air, or when it is brought into directcontact with water. The diffusion process is controlled by the watercontent of the skin as well as the concentration gradient. In a very dryenvironment the water loss from the external skin layers can besignificant and often exceeds the rate of replacement by diffusion. Anocclusive barrier placed onto the surface of the skin acts to retard thewater loss to the environment and allows the skin surface to rehydrateby the diffusion process. Due to the effectiveness and safety of thealkylmethyl polysiloxanes they serve as useful skin conditioners,occlusive moisturizers and contribute to dry skin prevention byprotection and moisture retention as well as dry skin repair byemolliency, lubricity and moisture restoration.

The cyclic alkylmethylsiloxanes of the present invention are provided inan amount sufficient to provide the desired properties (e.g.occlusivity, substantivity, etc.) to the skin. The total amount ofcyclic alkylmethylsiloxane in any formulation will vary depending on theadditional components present. Generally, the amount of cyclicalkylmethylsiloxane present will comprise between about 1 and about 90weight percent of the final formulation.

Volatile solvents which may be employed to deliver the alkylmethylpolysiloxane to the skin include aliphatic hydrocarbons among which areisoparaffins such as a C10-11 Isoparrafin (sold by Exxon as ISOPAR G);aliphatic alcohols such as isopropyl alcohol and ethyl alcohol;aliphatic esters such as isopropyl myristate and ethyl acetate; andvolatile siloxanes. The solvent can also be a linear or cyclicpolysiloxane. The solvent must be compatible with and capable ofdissolving, dispersing, or suspending the alkylmethyl polysiloxane andany optional component which may be present. Volatile siloxanes whichmay be employed as solvents include the volatile low viscosity cyclicsilicone fluids and linear silicones. Representative of these materialsare polydimethylcyclosiloxane and hexamethyldisiloxane. Such fluids haveviscosities of 0.65 to 5.0 centistokes measured at twenty-five degreesCentigrade. Non-volatile solvents can also be employed in the presentinvention. Non-volatile oils commonly utilized in cosmetic applicationsare suitable for use as solvents in the present invention.

The volatile cyclic silicones conform to the formula (R₂ SiO)_(x) inwhich R is an alkyl radical having from one to three carbon atoms or aphenyl group. Typically the cyclic siloxanes have the formula (CH₃)₂SiO!_(x) in which x is an integer from three to ten. Volatile cyclicsiloxane compounds found to be especially useful in accordance with thepresent invention are the tetramer compound octamethylcyclotetrasiloxaneand the pentamer compound decamethylcyclopentasiloxane. Mixtures of thetetramer and pentamer may also be employed. Such cyclic siloxanes haveviscosities ranging from about 2.5 centistokes to about fivecentistokes. These materials are also known under The Cosmetics,Toiletries and Fragrance Association designation as cyclomethicone.

Volatile low viscosity linear silicone fluids which may be employed assolvents have the formula R₃ SiO(R₂ SiO)_(n) SiR₃ in which R is an alkylradical having one to six carbon atoms and n is an integer of from twoto nine. Representative of the linear siloxane is hexamethyldisiloxaneof the formula ##STR6## which has a viscosity of 0.65 centistokesmeasured at twenty-five degrees Centigrade.

The cyclic low viscosity volatile silicones are clear fluids and areessentially odorless, nontoxic, nongreasy and nonstinging. Cosmeticallythey are nonirritating to the skin and possess the properties of goodspreadability and ease of rub-out. The materials evaporate leavingbehind no residue.

In addition to the volatile solvent and the cyclic alkylmethylpolysiloxane, skin care formulations in accordance with this inventionmay optionally contain other emollients, sunscreens, and adjuvants suchas perfumes, fragrances and preservatives. Examples of other emollientsand moisturizers which may be included in compositions of this inventioninclude straight, branched or cyclic hydroxy compounds such as alcoholscontaining 1 to 30 carbon atoms; straight, branched or cyclic carboxylicacids containing 1 to 31 carbon atoms; acid esters containing C₁ to C₃₀carboxylic acids esterfied with C₁ to C₃₀ alcohols; alcohol etherscontaining 1 to 30 carbon atoms; and alkanes of the formula H-(CH₂)n-Hwherein n is 5 to 30. Examples of such materials include 2-ethylhexyloxystearate; arachidyl propionate; 2-ethylhexyl adipate; isopropylmyristate; stearyl alcohol; propylene glycol; propionic acid; stearicacid; polyoxypropylene cetyl alcohol; polyoxypropylene lanolin alcohol;Carbowax" 300; petroleum jelly; mineral oil; aliphatic hydrocarbons suchas mineral spirits; lanolin and lanolin derivatives such as acetylatedlanolin and isopropyl lanolate.

Sunscreens are evaluated according to their ability to slow the erythemaor sunburn resulting from the exposure of skin to ultraviolet lightbetween about 290-320 nanometers (the UV-B region). This is accomplishedby absorbing damaging radiation before the radiation contacts the skinsurface. Para-aminobenzoic acid derivatives and cinnamates such as octylmethoxycinnamate are examples of preferable and commercially employedcategories of sunscreen active compounds. UV-A region agents capable ofabsorbing ultraviolet light in the range of 320-400 nanometers are alsouseful in accordance with the present invention including benzophenonesand materials such butyl methoxy dibenzoylmethane. Some additionalexamples of sunscreen chemicals which may be employed in accordance withthe present invention are 2-ethoxyethyl p-methoxycinnamate; menthylanthranilate; homomenthyl salicylate; glyceryl p-aminobenzoate; isobutylp-aminobenzoate; isoamyl p-dimethylaminobenzoate;

2-hydroxy-4-methoxybenzophenone-5-sulfonic acid;

2,2'-dihydroxy-4-methoxybenzophenone;

2-hydroxy-4-methoxybenzophenone; 4-mono and

4-bis(3-hydroxypropyl)amino isomers of ethyl benzoate; and

2-ethylhexyl p-dimethylaminobenzoate.

One compound in accordance with formula (II) is the tetradecylfunctionalcyclic alkylmethylpolysiloxane of the formula (C₁₄ H₂₉ OMeSi)₄ in whichx is four, y is zero and z is thirteen. The durability and substantivityof this material is shown below.

EXAMPLE I

In order to illustrate the durability of the cyclic alkylmethylpolysiloxanes of the present invention in comparison to other materialsdescribed in the art, data was collected by employing a soap washingprocedure that involved the measurement of substantivity on human skin.Materials that were tested included (A) mink oil, (B) a linearalkylmethyl polysiloxane having the formula ##STR7## where the sum ofintegers x and y was six and the value of z was seventeen, and (C) acyclic alkylmethylpolysiloxane (C₁₄ H₂₉ OMeSi)₄. Sample (C) was amaterial in accordance with the present invention while Samples (A) and(B) were provided for comparative purposes. Sample (B) was theGoldschmidt ABIL silicone material mentioned in the "Background"section. ABIL silicone is described by the manufacturer as polysiloxanepolyalkylene copolymer and The Cosmetics, Fragrance & ToiletriesAssociation adopted name of the material is stearyl dimethicone. ABIL isa trademark of Tho Goldschmidt AG Chemische Fabriken, Goldschmidtstrasse100, D-4300 Essen 1. These materials are identified in the table belowas samples (A), (B) and (C) respectively. Specifically the method wasbased on Attenuated Total Reflectance/Fourier Transform InfraredSpectrophotometric (ATR/FTIR) analysis in which skin studies wereconducted and analyzed based on the reflection of energy at theprism/skin interface. Instrumentation included a NICOLET model 20DX FTIRsystem and a HARRICK Scientific Skin Analyzer. The ATR studies involvedcontact of the skin sample and prism. A hydration procedure was employedin order to increase the softness and flexibility of the skin surfacewhich resulted in a less variable contact between the skin and prism.This hydration procedure included placing a water soaked towel againstthe skin test site for one minute prior to actual spectra collection. Askin test site selected was an area of about eighty square centimetersand about eight to ten milligrams of each solution tested was applied tothe skin test site area in the form of a thin film using a small paintbrush. From the data collected it was possible to calculate percentagesof ingredients remaining on the skin following various soap washsequences. The soap employed was a 0.5 weight percent solution of"IVORY" bar soap and a soap rub is defined as two passes over the testarea with the soap solution cupped in the palm of the hand. One soapwash procedure included fifteen soap rubs and ten rinse rubs under coolrunning tap water. The test site was the volar forearm. The testsolutions were applied to the skin test site on the forearm in the formof a mixture of the test materials dissolved in a hydrocarbon solventsuch as ISOPAR G (a C10-C11 Isoparrafin sold by Exxon) or a volatilesilicone fluid of low viscosity such as polydimethylcyclosiloxane whichwas a mixture of tetramer and pentamer and having a viscosity of about2.5 centistokes measured at twenty-five degrees Centigrade. The solutioncontained ten to twenty percent by weight of the material in thesolvent. The solvent was allowed to evaporate from the volar forearmregion for fifteen to thirty minutes prior to the institution of themeasurement procedures. The site was hydrated as noted above and theinitial spectrum was collected.

A simplified test procedure is illustrated as follows. A test area onthe forearm was marked and the test area was washed with the soapsolution using fifteen rubs followed by rinsing with ten rubs under coolrunning water. Excess moisture was blotted from the forearm with atowel. After one minute the skin was hydrated for one minute using atowel saturated with water which was held loosely over the test area.Excess moisture was blotted and at the end of about fifteen to thirtyseconds a background scan was run. The test mixture was applied to theskin test area and the solvent allowed to evaporate. The skin was againhydrated for one minute and excess moisture was blotted off. Afterthirty seconds a scan was run of the test area which represented anInitial Condition. The test area was washed with the soap solution usingfifteen rubs followed by ten rinses and the excess moisture was blottedoff. After one minute the skin was hydrated for one minute, blotted andat the end of about fifteen to thirty seconds a scan was run of the testarea which represented a First Soap Wash Condition. Similar steps wererepeated for second, third, fourth and fifth soap wash conditions.Baselines for infrared bands were defined and band heights weremeasured. The percent ingredient remaining on the skin was calculatedusing these data.

Table I indicates the results obtained by following the precedingprocedure and shows that the amount of the cyclic alkylmethylpolysiloxane (C) on the skin following the fifth wash was six times theamount of mink oil (A) and double the amount of the Goldscmidt ABILsilicone described hereinabove (B). Thus the substantivity of the cyclicalkylmethyl polysiloxane for skin is substantial and unexpectedly muchgreater than the compounds described in the art.

                  TABLE I                                                         ______________________________________                                        Percent Remaining on Skin After Wash                                          Wash No.                                                                             Sample (A)    Sample (B)                                                                              Sample (C)                                     ______________________________________                                        1      23            43        53                                             2      9             37        45                                             3      6             24        39                                             4      3             22        37                                             5      5             17        32                                             ______________________________________                                    

EXAMPLE II

The procedure employed to collect the data shown in Table I was repeatedin order to compare the cyclic alkylmethylsiloxanes of the presentinvention with U.S. Pat. No. 4,784,844 and U.S. Pat. No. 5,002,762mentioned in the "Background" section. Octyl Methoxycinnamate (sold byGivaudan as Parsol MCX), a conventional sunscreen, was used forcomparative purposes and as a component in a skin care formulationapplied to the skin to test the ability of certain alkylmethylsiloxanesto improve the substantivity of the skin care formulation.

Samples B, C, and D were solutions containing 20 weight percent (wt %)Parsol MCX (described hereinabove), 10 wt % silicone, and 70 wt %solvent (ISOPAR G (a C10-C11 Isoparrafin sold by Exxon)). The specificSamples contained: (A) Parsol MCX (a cinnimate sunscreen) at 20 wt % in80 wt % ISOPAR G, (B) a mixture of Parsol MCX, ISOPAR G, and analkylmethylpolysiloxane (C₆ H₁₃ MeSiO)₄, (C) a mixture of Parsol MCX,ISOPAR G, and a cyclic alkylmethylpolysiloxane (C₁₄ H₂₉ MeSiO)₄, and (D)a mixture of Parsol MCX, ISOPAR G, and a cyclic alkylmethylpolysiloxane(C₂₀ H₁₃ MeSiO)₅. These Samples were then tested according to theprocedure of Example I described hereinabove.

Samples (C) and (D) were materials in accordance with the presentinvention while Samples (A) and (B) were provided for comparativepurposes. Sample (A) contained no alkylmethylpolysiloxane, and theSample (B) siloxane was of significantly lower molecular weight thanSample (C) or (D). The Sample B silicone is believed to be fairlyrepresentative of the compositions taught in both U.S. Pat. No.4,784,844 and U.S. Pat. No. 5,002,762 mentioned hereinabove. Thesematerials are identified in Table II below as samples (A), (B), (C), and(D) respectively.

Table II below describes the results obtained by following the procedureof Example I and shows that the amount of sunscreen remaining on theskin following the third wash was substantially greater for Samples (C)and (D) when compared to the Parsol MCX solution (Sample A) and thelower molecular weight cyclic alkylmethyl polysiloxane (Sample B). AsTable II below shows, the present invention retained up to 2.5 timesgreater the amount of sunscreen on the skin than the low molecularweight siloxanes described in the '844 patent or the '762 patentretained. In fact the lower molecular weight siloxane (Sample B) appearsto have actually had a negative effect on the inherent substantivity ofthe sunscreen. This negative effect is indicated by Sample B having alower percentage of sunscreen remaining on the skin than does thesolution containing the sunscreen alone (Sample A).

Thus the cyclic alkylmethyl polysiloxanes of the instant invention aresubstantivity aids of unexpectedly greater efficacy than the compoundsdescribed in the art.

                  TABLE II                                                        ______________________________________                                        Percent Remaining on Skin After Wash                                          Wash No.                                                                              Sample (A)                                                                              Sample (B)                                                                              Sample (C)                                                                            Sample (D)                                ______________________________________                                        1       49        23        49      75                                        2       29        16        33      57                                        3       18        14        22      59                                        ______________________________________                                    

EXAMPLE III

The occlusive film forming ability of the present invention wasdemonstrated by conducting measurements of water loss by using an invitro water vapor permeability test method. The rate of water loss wasmeasured by charging stainless steel Payne permeability cups with 3milliliters of H₂ O and covering the cups with collagen films spreadwith a thin coating of the material to be tested. The assembly is thenplaced in an oven at low humidity and skin temperature. Weight lossmeasurements are taken over time to obtain water loss rates. The resultsof these tests are set forth in Table III below and indicate that thealkylmethylpolysiloxanes of the present invention decrease the watervapor permeability of a substrate by the formation of an occlusivebarrier on a substrate (such as skin) which retards the rate ofpenetration of water vapor from the substrate through the film. SamplesA, B, and C were all tested at 100 weight percent. Experimentation hasdemonstrated a direct relationship between the ability of materials todecrease water vapor permeability in this test and their ability toreduce transepidermal water loss in vivo.

                  TABLE III                                                       ______________________________________                                        In Vitro Water Vapor Permeability (WVP)                                       of Alkylmethyl Polysiloxanes                                                  Material    Water Loss Rate (g/m.sup.2 /h)                                    ______________________________________                                        Sample A    106                                                               Sample B    89                                                                Sample C    84                                                                ______________________________________                                    

In Table III Sample A is a cyclic alkylsiloxane described in U.S. Pat.No. 4,784,844 and U.S. Pat. No. 5,002,762 cited hereinabove and has theformula (C₆ H₁₃ MeSiO)₄, Sample (B) is a cyclic alkylmethylsiloxane ofthe present invention and has the formula (C₁₄ H₂₉ MeSiO)₄, and Sample Cis also a cyclic alkylmethylsiloxane of the present invention and hasthe formula (C₂₀ H₄₁ MeSiO)₅. It can clearly be seen from the data shownin Table III that the compositions of the present invention unexpectedlyreduce water loss far more effectively than the compositions describedin the above mentioned patents.

EXAMPLE IV

The occlusive film forming ability of the present invention was againdemonstrated by conducting measurements of water loss by using the invitro water vapor permeability test method described hereinabove. Theamounts of cyclic alkylmethylsiloxane and solvent(a C10-C11 Isoparrafinsold by Exxon as ISOPAR G) utilized in this example along with theresults of these tests are set forth in Table IV below and indicate thatthe alkylmethylpolysiloxanes of the present invention decrease the watervapor permeability of a substrate by the formation of an occlusivebarrier on a substrate (such as skin) which retards the rate ofpenetration of water vapor from the substrate through the film.

                  TABLE IV                                                        ______________________________________                                        In Vitro Water Vapor Permeability (WVP)                                       of Alkylmethyl Polysiloxanes                                                  Material                                                                             Siloxane (wt %)                                                                            Solvent Water Loss Rate (g/m.sup.2 /h)                    ______________________________________                                        Sample A                                                                              5           95      132                                                      25           75      135                                                      50           50      133                                                      75           25      133                                               Sample B                                                                              5           95      138                                                      25           75      137                                                      50           50      134                                                      75           25      124                                               Sample C                                                                              5           95      142                                                      25           75      134                                                      30           70      120                                                      40           60       47                                                      50           50       54                                                      75           25       45                                               Untreated                   124                                               Collagen                                                                      Control                                                                               0           100     133-145                                           ______________________________________                                    

In Table IV Sample A is a cyclic alkylsiloxane described in U.S. Pat.No. 4,784,844 and U.S. Pat. No. 5,002,762 cited hereinabove and has theformula (C₆ H₁₃ MeSiO)₄, Sample (B) is a cyclic alkylmethylsiloxane ofthe present invention and has the formula (C₁₄ H₂₉ MeSiO)₄, and Sample Cis also a cyclic alkylmethylsiloxane of the present invention and hasthe formula (C₂₀ H₄₁ MeSiO)₅. It can clearly be seen from the data shownin Table III that the compositions of the present invention unexpectedlyreduce water loss far more effectively than the compositions describedin the above mentioned patents.

EXAMPLE V

The procedure employed to collect the data shown in Table I and Table IIwas again repeated in order to show the substantivity of the presentinvention at varying concentrations. Octyl Methoxycinnamate (sold byGivaudan as Parsol MCX), a conventional sunscreen, was used forcomparative purposes and as a component in a skin care formulationapplied to the skin to test the ability of certain alkylmethylsiloxanesto improve the substantivity of the skin care formulation.

The materials that were tested were solutions containing Parsol MCX(described hereinabove), silicone, and solvent (ISOPAR G (a C10-C11Isoparrafin sold by Exxon)). The amounts of each component are reportedin Table V along with the results of the tests performed. The siliconetested in this Example was an alkylmethylpolysiloxane (C₂₀ H₄₁ MeSiO)₅.These Samples were then tested according to the procedure of Example Idescribed hereinabove. All amounts in Table V are reported as weightpercent (wt %).

Table V below describes the results obtained by following the procedureof Example I and shows that the amount of sunscreen remaining on theskin following the third wash was substantially greater for Samples thatcontained an alkylmethylsiloxane of the present invention as compared tothose that contained no silicone component.

                  TABLE V                                                         ______________________________________                                        SUBSTANTIVITY                                                                 Parsol MCX                                                                            Siloxane     Solvent % Remaining After                                (wt %)  (wt %)       (wt %)  Wash 3                                           ______________________________________                                        10      0            90      39                                               20      0            80      20                                                5      0            95      33                                               20      10           70      59                                               20      5            75      47                                               10      10           80      56                                               10      5            85      44                                               10      2            88      46                                               10      1            89      60                                                5      1            94      41                                               ______________________________________                                    

The following examples illustrate the method of making the cyclicalkylmethylsiloxanes of the present invention.

EXAMPLE VI Synthesis of Cycloalkylmethylsiloxanes

Approximately 115 grams (1 mole) of MeHSiCl₂ dissolved in 120 grams oftoluene was added to a flask containing 500 grams of de-ionized waterwhich was rapidly stirred in order to achieve good mixing during theaddition. The products of this hydrolysis reaction were two incompatiblelayers. The upper layer was approximately 180 grams containing 60 gramsof (MeHSiO)x cyclosiloxanes with the value of x ranging from 4 to 7dissolved in toluene (33% silicone), while the lower layer wasapproximately 570 grams of 12% HCl in water.

The two layers were separated and the toluene layer was washed to removeresidual acid. The toluene layer was then treated with anhydrous calciumcarbonate to remove any residual acid as well as water. This materialwas then distilled to separate the toluene, (MeHSiO)₄ and (MeHSiO)₅.Higher molecular weight cyclosiloxanes were not distilled. These can berecycled in the hydrolysis process. Approximately 25 grams (83% totalyield) of each of (MeHSiO)₄ and (MeHSiO)₅ were obtained. The productswere identified by analytical comparison (Gas Chromatography and MassSpectrometry) with authentic standards.

To a mixture of 206 grams (1.05 mole) of tetradecene and 1.0 gram of0.5% platinum on carbon heated at 100° C. without agitation was addeddropwise 60 grams (0.25 mole) of pure (MeHSiO)₄ over a period of onehour. After complete addition of the cyclosiloxane hydride, the mixturewas heated to 100° C. for two hours, cooled to 40° C. and filtered. Theproduct (C₁₄ H₂₉ MeSiO)₄ was allowed to cool to room temperature. Theproduct was a wax with a softening point of 27° C.

EXAMPLE VI-A Synthesis of Cyclo(alkylmethyl-dimethylsiloxanes)

Approximately 115 grams (1 mole) of MeHSiCl₂ and 1161 grams (9 moles) ofMe₂ SiCl₂ dissolved in 1500 grams of toluene were added to a flaskcontaining 5000 grams of de-ionized water, which was rapidly stirred inorder to achieve good mixing during the addition. The products of thishydrolysis reaction were two incompatible layers. The upper layer wasapproximately 2225 grams containing 725 grams of cyclosiloxanesdissolved in toluene (33% silicone), while the lower layer wasapproximately 5700 grams of 13% HCl in water.

The two layers were separated and the toluene layer was washed to removeresidual acid. The toluene layer was then treated with anhydrous calciumcarbonate to remove any residual acid as well as water. This materialwas then distilled to separate the toluene and the cyclosiloxanes. Afterremoval of the toluene, the cyclosiloxanes were seperated bydistillation in the following order:

    ______________________________________                                        a)    (Me.sub.2 SiO).sub.3 (MeHSiO).sub.1                                                         --        100 grams (0.35 mole)                           b)    (Me.sub.2 SiO).sub.4                                                                        --        160 grams (0.54 mole)                           c)    (Me.sub.2 SiO).sub.4 (MeHSiO).sub.1                                                         --        144 grams (0.40 mole)                           d)    (Me.sub.2 SiO).sub.5                                                                        --        150 grams (0.40 mole)                           e)    (Me.sub.2 SiO).sub.5 (MeHSiO).sub.1                                                         --         60 grams (0.14 mole)                           f)    (Me.sub.2 SiO).sub.6                                                                        --         40 grams (0.09 mole)                           ______________________________________                                    

No further materials were distilled and the siloxane residue was 75grams. This material can be recycled in the hydrolysis process. Theabove materials were identified by Gas Chromatography and MassSpectrometry.

To a mixture of 80 grams (0.315 mole) of 1-octadecene and 1.0 gram of0.5% platinum on carbon heated at 100° C. without agitation was addeddropwise a mixture of 100 grams (0.30 equivalents of Si--H) of 40 wt. %(Me₂ SiO)₃ (MeHSiO)₁, 45 wt. % (Me₂ SiO)₄ (MeHSiO)₁ and 15 wt. % (Me₂SiO)₅ (MeHSiO)₁ over a period of one hour. After complete addition ofthe cyclosiloxane hydride mixture, the resultant mixture was heated at100° C. for an additional two hours, cooled and filtered. The product, amixture of (C₁₈ H₃₇ MeSiO)₁ (Me₂ SiO)₃₋₅ cyclosiloxanes was a clear,colorless, odorless liquid.

EXAMPLE VI-B

The method described in Example IV-A hereinabove was used to produce thecyclosiloxanes in this example.

To a mixture of 155 grams (0.615 mole) of 1-octadecene and 1 gram of0.5% platinum on carbon heated to 100° C. without agitation was addeddropwise a mixture of 100 grams (0.585 equivalents of Si--H) of anaverage composition of (MeHSiO)₂ (Me₂ SiO)₂₋₄ cyclosiloxanes over aperiod of one hour. After complete addition of the cyclosiloxane hydridemixture, the mixture was heated at 100° C. for an additional two hours,cooled and filtered. The product, a mixture of an average composition of(C₁₈ H₃₇ MeSiO)₂ (Me₂ SiO)₂₋₄ cyclosiloxanes was a white, odorless waxwith a softening point of approximately 25° C.

It should be apparent from the foregoing that many other variations andmodifications may be made in the compounds, compositions and methodsdescribed herein without departing substantially from the essentialfeatures and concepts of the present invention. Accordingly it should beclearly understood that the forms of the invention described herein areexemplary only and are not intended as limitations on the scope of thepresent invention as defined in the appended claims.

That which is claimed is:
 1. A method of treating human skin to decreasetransepidermal water loss by applying to the skin a film formingconditioning formulation comprising an effective amount of anon-volatile alkylmethyl cyclic polysiloxane copolymer having theformula ##STR8## in which x and y are integers the sum of which is four,five, or six provided that x and y cannot be zero; z is an integerhaving a value of eleven to about twenty-nine; and R is an alkyl grouphaving one to six carbon atoms.
 2. A method of treating human skin todecrease transepidermal water loss by applying to the skin a filmforming conditioning formulation comprising an effective amount of anon-volatile alkylmethyl cyclic polysiloxane copolymer having theformula ##STR9## in which x and y are integers the sum of which is four,five, or six provided that x and y cannot be zero, and z is an integerhaving a value of eleven to about twenty-nine.
 3. The method of claim 2in which x is one, y is three, four, or five, and z is eleven totwenty-nine.
 4. The method of claim 2 in which x is two, y is two,three, or four, and z is eleven to twenty-nine.
 5. The method of claim 2in which x is three, y is one, two, or three, and z is eleven totwenty-nine.
 6. The method of claim 2 in which x is four, y is one ortwo, and z is eleven to twenty-nine.
 7. The method of claim 2 in which xis five, y is one, and z is eleven to twenty-nine.
 8. The method ofclaim 2 in which the formulation is applied to the skin in the form of asolution of the cyclic alkylmethyl polysiloxane copolymer dissolved in avolatile solvent selected from the group consisting of aliphatichydrocarbons, aliphatic alcohols, aliphatic esters, low viscositysilicone fluids, and cyclic polysiloxanes.
 9. A film formingconditioning formulation for the treatment of human skin to decreasetransepidermal water loss from the skin comprising an effective amountof a non-volatile alkylmethyl cyclic polysiloxane copolymer having theformula: ##STR10## in which x and y are integers the sum of which isfour, five, or six provided that x and y cannot be zero; z is an integerhaving a value of eleven to about twenty-nine; and R is an alkyl grouphaving from one to six carbon atoms.
 10. A film forming conditioningformulation for the treatment of human skin to decrease transepidermalwater loss from the skin comprising an effective amount of anon-volatile alkylmethyl cyclic polysiloxane copolymer having theformula ##STR11## in which x and y are integers the sum of which isfour, five, or six provided that x and y cannot be zero, and z is aninteger having a value having a value of eleven to about twenty-nine.11. The formulation of claim 10 in which x is one, y is three, four, orfive and z is eleven to twenty-nine.
 12. The formulation of claim 10 inwhich x is two, y is two, three, or four and z is eleven to twenty-nine.13. The formulation of claim 10 in which x is three, y is one, two, orthree and z is eleven to twenty-nine.
 14. The formulation of claim 10 inwhich x is four, y is one or two and z is eleven to twenty-nine.
 15. Theformulation of claim 10 in which x is five, y is one, and z is eleven totwenty-nine.
 16. The formulation of claim 10 in which the formulation isa solution of the cyclic alkylmethyl polysiloxane copolymer dissolved ina volatile solvent selected from the group consisting of aliphatichydrocarbons, aliphatic alcohols, aliphatic esters, and low viscositysilicone fluids, and cyclic polysiloxanes.
 17. A method of enhancing thesubstantivity of conditioning compounds on human skin comprisingapplying to the skin an organosilicon skin conditioning compound, thecompound being applied to the skin by being dissolved in a medium, saidorganosilicon compound being an effective amount of a non-volatilealkylmethyl cyclic polysiloxane copolymer having the formula: ##STR12##in which x and y are integers the sum of which is four, five, or sixprovided that x and y cannot be zero, and z is an integer having a valueof eleven to about twenty-nine.
 18. The method of claim 17 in which z is11-29 and the medium is a volatile solvent selected from the groupconsisting of aliphatic hydrocarbons, aliphatic alcohols, aliphaticesters, and low viscosity silicone fluids, and cyclic polysiloxanes.